An engine has excessive valve guide wear. Technician A says to ream the guide and install a new valve with an oversized stem. Technician B says to knurl the valve stem and reinstall it in the guide. Who is right?

1. Technician A only.

2. Technician B only.

3. Both A and B

4. Neither A nor B.

Technician A only

Explanation:

Valve guide wear refers to excessive clearance between valve stem and valve guide. it is due to the constant friction between the guide and valve stem. It is recommended that to ream the valve guide and install a new valve with an over sized stem. knurling the valve stem and reinstall it in the guide is only for short term. For better life the valve one should ream the guide and install a new valve with an over sized stem. hence Technician A is correct